1. Field of the Invention
The present invention relates to an apparatus for fabricating semiconductor device including a step of treating the surface of a semiconductor layer with hydrogen, and a method for fabricating semiconductor device including a step of treating the surface of the semiconductor layer with hydrogen. Particularly, the present invention relates to a method and an apparatus for removing a natural oxide layer from the surface of a silicon layer and moreover terminating the surface of the silicon layer using hydrogen, and a method for fabricating a semiconductor device including the above steps.
2. Description of the Related Art
The following are known as the existing methods for removing a natural oxide layer from the surface of a semiconductor wafer and hydrogen-terminating the surface of the semiconductor wafer: the wet treatment using diluted hydrofluoric acid described in the following document [1], the dry treatment using hydrogen plasma described in the following document [2], and the dry treatment using hydrogen atoms (hydrogen radicals) described in the following document [3].
[1] G. S. Higashi et al., J. Appl. Phys. Lett., Vol.56, No.7, 1990, pp.656-658 PA1 [2] A. Kishimoto et al., Jpn. J. Appl. Phys., Vol. 29, No.10, 1990, pp.2273-2276 PA1 [3] T. Takahagi et al., J. Appl. Phys., Vol.68, No.5, 1990, pp.2187-2191.
Among the above methods, the wet treatment using diluted hydrofluoric acid makes it possible to obtain a stable surface hardly reacting on other elements for a (111) plane of silicon. However, there is no stability for a (100) plane of silicon. Moreover, because of the wet treatment, fluorine may be left on the surface of a semiconductor wafer. Furthermore, it is difficult to connect a wet treatment apparatus with a dry treatment apparatus. Therefore, the dry treatment is desirable because it allows the apparatuses to easily connect each other.
The dry treatment using hydrogen plasma may damage the surface of a silicon substrate because high-energy particles collide with the surface.
The dry treatment using hydrogen radicals does not have the above problems. However, it is described in the above document [3] that the treatment took a long time at the hour order. Therefore, this dry treatment cannot practically be used.
As another type of dry treatment, a method for removing a natural oxide layer by transforming hydrogen fluoride (NF.sub.3) and hydrogen (H.sub.2) into plasma is disclosed in the official gazette of Japanese Unexamined Publication (KOKAI) No. Hei. 2-77124. The inventors of the present invention confirmed that a natural oxide layer was removed by this method. However, at the same time, the fact was found that the inner surface of a silica tube constituting a reaction chamber was etched and roughened.
It is an object of the present invention to provide a method and an apparatus for treating the surface of a semiconductor layer to shorten the time consumed for oxide layer removal and hydrogen termination by means of dry treatment, and moreover prevent the inner surface of a silica tube serving as a reaction chamber from roughening, and a method for fabricating a semiconductor device including the above steps.